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Advice On L24 Ignition Curve


Kent

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Hi Guys,

 

Just a little background, i have a relatively stock 1970 240Z (early vin) which has from what i understand a relatively stock engine (L24 with original dual SU's and aftermarket headers and exhaust system). The car ran well until i put it into storage a couple of years ago.. after maintenance etc. the car ran, but the rear carb was overly rich.

 

Instead of messing around with it, i decided to fit the triple 40DCOE's i had been itching to put on the car. I fitted these, along with a carter fuel pump (and FPR/filter), new ignition leads and an electronically programmable distributor (from 123ignition.nl) rather than getting the standard one recurved

 

Fitting all went relatively well without any major dramas, however i was unable to get the webers to even get to idle (the webers themselves were straight off a running car). Interestingly i can't get a solid timing light off Cylinder 1 (even though i checked TDC and firing order etc), however i can read the correct indicated/programmed timing mark off of cylinder 6

 

Spent many weekends playing with the webers, with every result being that the car would idle ok until it got any amount of heat into it and then would pop and fart with absolutely no power off idle.

 

I finally gave up and booked it into a professional tuner, its due to get towed in Friday morning.. He seems on point with the webers, though he hasn't got any experience with the L24 (trying to spoon feed him the relevant info he might need from the engine service manuals). But he is an older gentleman and rather taken back by the idea of a bluetooth distributor.

 

I am not sure what Distributor i originally had on the car (it's in storage now), but i have loaded the attached ignition curve onto the Dizzy (which was advised on http://forums.hybridz.org/topic/127119-123ignition-timing-maps-for-40dcoes)

 

I can't say i have much knowledge on Distributors, but from what i can read off the engine manuals, the default is Factory idle at 750rpm and 17degrees timing at 550 (contrary to the curve i have)

 

adjusting the curve to me, doesn't seem like a hard thing, but i can understand that he is not used to this.

 

Can someone with some knowledge have a look at the curve and let me know if it will cause any major tuning troubles? (the "anti-stall" feature 500rpm threw him too.. this may be more confusing for him than useful). Appreciate any help anyone can give.. its been driving me nuts, and it would be nice to have the car back on the road

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To my eyes it should run on that.

However I suggest you remove the dip @ 1000rpm & continue adding timing from idle. Maybe try backing the timing off to 7deg at 500rpm.
Personally I'd have full advance at all in at 3000rpm... 34deg total is fine, so long as it doesn't detonate (ping).

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Thanks for the advice guys.. i will follow the directions and adjust the curve to 7'@500, 17'@1000, 34'@3000 and leave it at that. or is the 7' to 17' ramp up too quick?

 

Yep, its the Bluetooth Datsun version of the 123ignition dizzy (123\TUNE+-6-R-V-DATSUN).

 

I bought it through 123ignition.com.au, it had to be ordered in for me, but it came relatively quickly.. and pretty good pricing compared to the O/S pricing

 

I had read some problems on other forums with the shaft key not fitting correctly, but mine was perfectly fine (i assume the problem has been resolved in production). It does rotate the location of your TDC #1 plug though if you have custom leads.

 

It was all new to me but i didn't have a problem fitting it, and although the calibration it uses (turning the dizzy on and rotating until a light changes), seems like it is open to large tolerances.. mine seems to be perfect. I didn't get any decent install photos apart from the attached.. it certainly doesn't look out of place

 

Did you upgrade the coil for electronic ignition and remove balast resistor?

I run idle @1000rpm 17deg static

 

I did, i asked for advice and was recommended to replace my coil with their 1.8 ohm Red "Beru ZS109" coil, which i ordered along with the dizzy. I bypassed the resistor, but i did use the one side of the resistor as a connection post for the coil still (other side isn't connected), mainly because i couldn't be stuffed rewiring too much

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Edited by Kent
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Sounds like a good option, although I kind of like the idea of retaining a mechanical unit etc.. call me weird but I find that kind of stuff quite charming. :D

 

However I do like the idea of being able to dynamically adjust the timing, could be good for tuning for different octane fuels.

 

A couple of questions:

1.) What does the L-series unit cost?

2.) Can you get a black distributor cap for it? Red stands out a bit much..

3.) Would be good to have a black coil too (keep it looking OEM). I know this is minor.

4.) So I take it there is no vacuum advance anymore? How does it handle / adjust for small throttle inputs? Or is it a fixed advance curve?

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Hi gav,

 

The dizzy and coil wasn't a cheap solution, although they have i think a cheaper USB cable version (missing the BT), but it seemed to be a true plug in and comparable to having to set up ignition triggers etc. in some of the other systems. I have never had much dealing with carb's, dizzy's etc. and i didn't want to get my standard dizzy recurved, so it seemed a good option for me. I don't know what the cost would be now.. mine was the first BT one they had in, but they may hold stock locally now.

 

As for the cap and coil, 123ignition didn't have black options when i purchased, but my research around the time found that it was compatible with some other bosch cap, so there may be a black option. Same with the coil.. you don't have to use theirs, but they do have requirements around the resistance.. I chose to go with their recommendations. My car wouldn't pass for concourse, especially installing the webers so it wasn't a huge priority (getting the car running was/is)

 

The system does have a vacuum port, and a separate vacuum advance curve in the software. with the factory SU's it would have worked well. I would have loved to keep it for economy with the webers,  However with the redline manifold i have, i couldnt find a simple solution to get the right vacuum

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Thanks for the advice Lurch, HKSZ and Gareth

 

I ended up with the following curve that seems to have met everyones suggestions, amazingly it was able to drive under its own power at least 500m this morning! (even if it was down hill). it's heading off to get tuned now.

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Edited by Kent
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Just a very quick update.. the webers were successfully tuned on this curve, and runs quite well (although he needs to order me in some 110 mains, its still a little rich on 115's).

 

I have to say, the software is still a little buggy at the current version when changing the curve, but this doesn't happen often, its definitely a solid solution.. just wish i could get the vacuum advance working with the weber manifold

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  • 2 weeks later...

The Anti stall dip you had before does work. (this is the cool thing with this distributor its not a recurved but programmable)

I am using it and with this, mine idles even when it goes to 500 rpm.

With 7° mine would never run.

 

Try once at your first curve to take off point 4 and point 5, set point 6 to 3000rpm.

 

I will try soon to use the manifold vacuum and programm it above 1500rpm to kick in.

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Hi Munters,

 

Back when i posted, i was in a bit of a fix with the car not running and upcoming registration inspection required.. It didn't help that i had changed a bunch of critical components at once.. try as i could i couldn't get the original map i posted to run the car.. strange as the mappings were not too dissimilar

 

now the car is running happily on the 2nd curve, i can look at re-introducing the anti-stall dip knowing i am starting from a decent base.. i was impressed with the original thought behind this dip, so i would like to introduce it again

 

would love to know how you get on with the manifold vacuum install.. There seems to be some real benefit from it, and it would be easy to do on an SU setup.. however i have not found a definitive posting on how to achieve this with the triple weber manifolds.. 

 

keen to see your curves (with engine setup spec's) once your done!

Edited by Kent
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I like that the BT model has an anti theft capability via a PIN code.

 

Edit:

Also the option of a rev limiter.

 

Sounds like a very good option if you are considering an upgrade or should one just stick to a High Energy Bosch Electronic distributor??

Edited by AndBir
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